The present invention relates to a molded-case circuit breaker or circuit breaker for distribution used to protect low-voltage distributing facilities from an excessive current, more specifically, to a circuit breaker equipped with an auxiliary switch and an alarm switch acting as internally attached devices (optional parts) for detecting the ON/OFF state of a main circuit contact or a tripping operation through an electric signal.
FIG. 7 shows a conventional configuration of a molded-case circuit breaker comprising a circuit breaker body equipped with an auxiliary switch as an internally attached device (optional part). In this figure, reference numeral 1 denotes a case (resin-molded case) of the circuit breaker body having a main-circuit breaking section 2, an opening and closing mechanism section 3, and a tripping section 4 integrated therein. In this configuration, a main circuit contact of the breaking section 2 is opened or closed by means of the opening and closing mechanism section 3 based on a manual operation of a handle 5. If an excess current flows through a main circuit, an output signal from the tripping section 4 trips the opening and closing mechanism section 3 to open the main circuit contact. The opening and closing mechanism section 3 is combined with an opening and closing lever 6 to link its tip to an assembly (not shown) of movable contact shoes of the breaking section 2, so that the opening and closing lever 6 can be pivoted and operated in response to the operation of the opening and closing mechanism section 3, thereby opening or closing the main circuit contact.
Further, an auxiliary switch 7 as an internally attached device is installed as a cassette in an attached unit housing section formed on a top surface of the case 1. At this installed position, an operating lever 7a drawn out from the auxiliary switch 7 is placed opposite an outputting projecting piece 6a formed on the opening and closing lever 6, so that a contact of the auxiliary switch 7 can be opened and closed in response to an opening or closing operation of the main circuit contact to detect the ON/OFF state of the main circuit as an electric signal.
In addition to the above configuration, another circuit breaker is known, wherein an alarm-outputting plate that slides in response to a tripping operation of the circuit breaker is combined with the opening and closing mechanism section, so that a mechanical output signal from the alarm-outputting plate can be transmitted to an alarm switch of an internally attached device to open or close the switch, thereby enabling detection of the tripping operation through an electric signal.
In the conventional circuit breakers, the auxiliary switch and the alarm switch as internally attached devices have individually designated installation positions. When the switches are set at these designated positions, the auxiliary switch and the outputting projecting piece of the opening and closing lever, and the alarm switch and the outputting projecting piece of the alarm-outputting plate are respectively linked on a one-to-one correspondence basis.
This makes it impossible to combine these switches flexibly such that the existing auxiliary switch is replaced with an alarm switch, or the alarm switch is replaced with an auxiliary switch, depending on a user""s specification.
The present invention has been made in view of this shortcoming, and an object of the invention is to provide an improved circuit breaker having an extended using range, such that the auxiliary and the alarm switches installed in the circuit breaker main body as internally attached devices can be installed in an arbitrary combination, without restriction to their installation positions.
To attain the above objective, the present invention is directed to a circuit breaker having a mechanism for opening and closing a main circuit contact, including a pivoting opening and closing lever and an alarm-outputting plate that operates in response to a tripping operation. A case of a circuit breaker body has multiple switch housing sections formed on a top surface thereof laterally spaced apart from each other, on which installed are an auxiliary switch for detecting the ON/OFF state of the main circuit contact through an electric signal and/or an alarm switch for detecting the tripping operation through the electric signal. The opening and closing lever and the alarm-outputting plate are arranged opposite to the switch housing sections to correspond to the respective housing sections such that the lever and plate have outputting projecting pieces laterally spaced apart from each other to transmit mechanical output signals to the attached switches set in the housing sections. The outputting projecting pieces of the opening and closing lever are arranged to be offset laterally from the outputting projecting pieces of the alarm-outputting plate.
In the above configuration, the attached switches, namely the auxiliary switch and the alarm switch, each comprises an assembly of a cassette-type unit case installed in a unit housing section, i.e. switch housing section, of the case of the circuit breaker body, a contact mechanism integrated in the unit case, an operating lever for the contact mechanism, and an interlocking arm coupled to the operating lever and drawn out forward from the unit case. The interlocking arm of the auxiliary switch and the interlocking arm of the alarm switch are coupled at different positions, so that when the switches are integrated in the case, the interlocking arm of the auxiliary switch is linked to the outputting projecting piece of the opening and closing lever, while the interlocking arm of the alarm switch is linked to the outputting projecting piece of the alarm-outputting plate.
In the above configuration, the auxiliary and alarm switches in the case of the circuit breaker main body as the attached switches (internally attached devices) can be installed in any arbitrary combination, with no restrictions for the installation positions, thus significantly extending the variation range of the attached switches.
Further, the attached switches used as the auxiliary and alarm switches comprise common parts including the unit case, the contact mechanism, and the operating lever, and are allowed to function as the auxiliary or alarm switches simply by changing the attached position of the interlocking arm coupled to the operating lever, depending on the type of the attached switch, thereby enabling the use of the common parts.